That will happen if you are using port 139 instead of 445 doing an SMB scan to Windows 7 and up.
But generically speaking, make sure the port is 445(1) and if Windows 10, make sure the PC Domain name or Workgroup is before the username(2)
For the username, easiest method to get the exact right format is from the share within windows itself ala: <exactly how it shows within the brackets>
You also could update the printer, but it won't fix your issue here with the settings as they are now.